Display device

ABSTRACT

Provided is a display device having a storing circuit  21  section for storing image signals for controlling display and an active device section  22  for performing display control on the basis of the image signals stored by the storing circuit section  21,  provided in each dot as a minimum unit of display, thereby achieving space saving.

TECHNICAL FIELD

[0001] This invention relates to a display device. The invention isespecially effective for the reflective liquid-crystal display (LCD) ororganic EL display (OELD), which is intended to achieve space savingwhile reducing electric power.

BACKGROUND OF THE INVENTION

[0002] Recently, the display devices using liquid crystal (hereinafter,referred to as display) is spreading at conspicuous pace. The display ofthis type is low in power consumption and improved in saving space, incomparison with a CRT display. Accordingly, it is important to make useof the merits of such a display and produce a display that is lower inpower consumption and improved in saving space.

[0003]FIG. 15 is a block diagram of a system for providing display on adisplay device by a TFT display. This system is configured with adigital interface 100 and a TFT liquid crystal display panel 101. Thedigital interface 100 is configured, at least, with a CPU 100A, a RAM100B, a frame memory 100C and an LCD controller 100D. The CPU 100A isoperation control means for transmitting display data while exchangingdata with the RAN 100B as a general-purpose memory. Because this RAM100B is not especially used merely as a memory for display, there isnewly a need of a memory for storing the data for display. That is theframe memory 100C The frame memory 100C temporarily stores the displaydata in an amount of one screen of the liquid crystal panel 101C(hereinafter, the data in an aunt of one pixel is given display data,and each binary signal constituting the display data is referred to asan image signal). The LCD controller 100D carries out transmissioncontrol of display data in order to display, in timing, each of displaydata stored in the frame memory 100C in a display position on the liquidcrystal panel 101C. Herein, for a CRT there is a necessity to transmitdisplay data through conversion into analog data. It is howeverconsidered that the interface of the liquid crystal display iscompatible with digital data, and herein the display data is transmittedby an image signal as digital data.

[0004] Meanwhile, the TFT liquid crystal display panel 101 in configuredwith a scanning line driver 101A, a digital data driver 101B and aliquid crystal panel 101C. The scanning line driver 101A carries outdisplay control in a scanning line (row) direction on the basis of thetiming data transmitted from the LCD controller 100D. The digital datadriver 101B is allowed to receive and process the digital-data imagesignal. The digital data driver 101B carries out display control in adata-line (column) direction on the basis of the timing data transmittedfrom the LCD controller 100D. On that occasion, it also controls thetonal levels of display. The liquid crystal panel 101C is a panel havingTFTs (Thin Film Transistors) to effect display under the control of thescanning line driver 101A and digital data driver 101B.

[0005] Such a system requires a frame memory 100C for temporarily storethe display data in an amount of all over the screen. Furthermore, anLCD controller 100D is required to transmit an image signal for thedisplay data to the digital data driver 101B.

[0006] Consequently, the system overall requires many of means thusincreasing its scale. Moreover, the reduction of consumed power cannotbe achieved because of a great deal of the amount of transmitting suchdata and large power consumption as a result thereof.

[0007] Therefore, it is a problem of the present invention to provide adisplay device capable of achieving space saving and consumed powerreduction for the system overall.

DISCLOSURE OF THE INVENTION

[0008] In order to solve the problem as above, a display deviceaccording to the present application comprises: a storing section forstoring a digital data signal for controlling display; and a displaycontrol section for performing display control on the basis of thedigital data signal stored by the storing section; provided in each dotas a minimum unit of display and arranged on a semiconductor orinsulating substrate.

BRIEF DESCRIPTION OP THE DRAWINGS

[0009]FIG. 1 is a block diagram representing a concept of a systemincluding a display device according to a first embodiment of thepresent invention.

[0010]FIG. 2 is a diagram representing in detail a drive section of apanel 1.

[0011]FIG. 3 is a diagram representing an equivalent circuit configuredin each dot of an active-matrix LCD section 2.

[0012]FIG. 4 is a diagram representing a relational example of drivewaveforms of VLC and VCOM.

[0013]FIG. 5 is a diagram representing each drive waveform example ofthe signals inputted by a row driver 3 and the digital data driver 4.

[0014]FIG. 6 is a diagram representing in detail a drive section of thepanel 1A according to a second embodiment of the invention.

[0015]FIG. 7 is a diagram representing an equivalent circuit configuredin each dot of an active-matrix OELD section 2A.

[0016]FIG. 6 represents a one-period waveform of PWMCLK in a thirdembodiment.

[0017]FIG. 9 is a diagram representing in detail a drive section of apanel 1B according to a fourth embodiment of the invention.

[0018]FIG. 10 is a diagram representing an equivalent circuit configuredin each dot of an active-matrix OELD section 2B.

[0019]FIG. 11 is a diagram representing in detail a drive section of apanel 1C according to a fifth embodiment of the invention.

[0020]FIG. 12 is a diagram representing an equivalent circuit configuredin each dot of an active-matrix LCD section 2C.

[0021]FIG. 13 represents a waveform of an alternating current signalVLCON in a fifth embodiment.

[0022]FIG. 14 is a diagram representing an equivalent circuit configuredin each dot in a sixth embodiment of the invention.

[0023]FIG. 15 is a block diagram of a system for performing display by adisplay device due to a TFT display.

[0024] Explanation of Reference Numerals

[0025]1, 1A, 1B, 1C Panel

[0026]2, 2C Active-matrix LCD section

[0027]2A, 2B Active-matrix OELD section

[0028]21, 21A, 21B Storing circuit section

[0029]22, 22A, 22B, 22C Active device section

[0030]23 PWM waveform forming circuit

[0031]24, 24A, LC section

[0032]25, 25A, OEL luminescent section

[0033]3 Row driver section

[0034]31, 31A Row decoder

[0035]32 Word line driver

[0036]4 Digital data driver section

[0037]41 Column decoder

[0038]42 Input control circuit

[0039]43, 43A, 43B Column selection switch section

[0040]5 Memory controller

[0041]6, 6A Timing controller

[0042]61 Address buffer

[0043]62, 62A, PWM timing signal generating circuit

[0044]110 Digital interface

[0045]110A CPU

DETAILED DESCRIPTION OF THE INVENTION

[0046] A display device comprises: a storing section for storing adigital data signal for controlling display; and a display controlsection for performing display control on the basis of the digital datasignal stored by the storing section; provided in each dot as a minimumunit of display and arranged on a semiconductor or insulating substrate.

[0047] In this display device, in order to control on-screen display,the storing section for storing a signal and the display control sectionfor controlling on-screen display on the basis of the signal stored bythe storing section are provided in each dot. Furthermore, they areintegrated on a semiconductor or insulating substrate, i.e. within eachdot array pattern. Power reduction in achieved by the space saving dueto the decrease of the circuits to be structured in an area other thanthe display region and storing all the signals required for on-screendisplay.

[0048] Also, a display device according to the invention comprises: astoring section configured by one or a plurality of storing circuitsprovided at each of interconnections of a plurality of write lines and aplurality of data lines correspondingly to an array pattern of a dot asa minimum unit of display so that, when a write signal is transmittedthrough the write line and an image signal as a digital data signal forcontrolling display is transmitted through the data line, the imagesignal is stored; a converting section for converting a value based on avalue of the image signal stored by the storing section into an analogsignal; and a display control section for performing tonal control usinga liquid crystal on the basis of an analog signal converted by theconverting section; provided in each dot as a minimum unit of displayand arranged on a semiconductor or insulating substrate.

[0049] In this display device, the storing section configured by one ora plurality of storing circuits is provided at each intersection of aplurality of write lines and a plurality of data lines, to store in thestoring section all the image signals required for on-screen display.The converting section converts the value based on the image signalsinto an analog signal on a dot-by-dot basis, and the display controlsection performs tonal control using a liquid crystal on the basis ofthe analog signal. These are integrated on a semiconductor or insulatingsubstrate, i.e. within each dot array pattern.

[0050] Also, in a display device according to the invention, the storingcircuit of the storing section is configured by a static circuit.

[0051] In this display device, the storing circuit is configured by astatic circuit thereby achieving to hold the image signals in a term aslong as possible.

[0052] Also, the converting section of the display device according tothe invention pulse-width-modulates the value based on the image signalto convert the same into the analog signal.

[0053] In this display device, the converting section performs pulsewidth modulation in converting the value based on the image signals intoan analog signal.

[0054] Also, the converting section of the display device according tothe invention converts the value based on the image signal into theanalog signal modulated to a pulse width based on a γ-characteristic.

[0055] In this display device, the converting section performs pulsewidth modulation based on a γ-characteristic in converting the valuebased on the image signals into an analog signal.

[0056] Also, the converting section of the display device according tothe invention performs conversion into the analog signal at a constantperiod interval.

[0057] In this display device, a constant period is provided as a unitbecause control is made by converting the value based on the imagesignals into a time based on a pulse width. Also, where display controlis made, for example, with a liquid crystal, there is a need to performrefresh at a constant time interval. For this reason, it is moreconvenient to perform conversion at a constant time interval

[0058] Also, in the converting section of a display device according tothe invention, provided is a duration that no conversion into an analogsignal is made in a duration of a constant period.

[0059] In this display device, a duration that no conversion into theanalog signal is made is provided in a duration of the constant period.In this duration, the image signals are changed to the storing section.

[0060] Also, in the converting section of a display device according tothe invention, a start time of the constant period is different betweenthe converting sections, and the period no conversion into the analogsignal is made is different.

[0061] In this display device, in order to suppress flicker, a starttime of the constant period is different between the convertingsections, and the duration no conversion into an analog signal is madeis different. Actually, this is made for each converting section on arow-unit or column-unit basis from a relationship of control, etc.

[0062] Also, an alternating current drive voltage is applied to thedisplay control section or a display device according to the invention.

[0063] In this display device, where display control is made using aliquid crystal, voltage application If deviated shorten the lifetimefrom the viewpoint of characteristics of a liquid crystal. Accordingly,an alternating current drive voltage is applied.

[0064] Also, in a display device according to the invention, thealternating current drive voltage is a voltage driven at VCOM±Va withrespect to a reference voltage VCOM.

[0065] In this display device, in order to suppress power consumption,the alternating current drive voltage is given a voltage driven atVCOM±Va so as to vary only the alternating current drive voltage on thebasis of a reference voltage.

[0066] Also, in a display device according to the invention, thealternating current drive voltage is a voltagealternating-current-inversion-driven by two voltage-applying lines laidcorrespondingly to the dot array pattern.

[0067] In this display device, in order to simplify the circuitconfiguration, the alternating current drive voltage is such a voltageas alternating-current-inversion-driven by two voltage-applying lineslaid correspondingly to the dot array pattern.

[0068] Also, a display device according to the invention, a plurality ofrows of the dot array are provided by groups, and rows in pair are setin each of the groups to invert a phase of the alternating current drivevoltage applied.

[0069] In this display device, in order to suppress flicker, rows inpair are set in each of the groups to invert a phase of the alternatingcurrent drive voltage applied.

[0070] Also, the display control section of a display device accordingto the invention controls light emission of current-driven luminescentdevices in connection an the basis of the analog signal in place ofperforming tonal control using a liquid crystal, thereby effecting tonalcontrol.

[0071] In this display device, the display control section is connectedwith current-driven luminescent devices spontaneously emitting light bycurrent drive so that emitted light is controlled on the basis of theanalog signal thereby achieving tonal control.

[0072] Also, a display device according to the invention comprises: astoring section configured by one or a plurality of storing circuitsprovided at each of interconnections of a plurality of write lines and aplurality of data lines correspondingly to an array pattern of a dot asa minimum unit of display so that, when a write signal is transmittedthrough the write line and an image signal as a digital data signal forcontrolling display is transmitted through the data line, the imagesignal in stored; one or a plurality of active devices providedrespectively connected to the storing circuits of the storing sectionand current-driven luminescent devices having areas corresponding toplace values represented by image signals stored in the storingcircuits, a display control section provided in each dot to controlemission of light of the current-driven luminescent devices on the basisof the values of the image signals stored in the storing circuits, andthese are arranged on a semiconductor or insulating substrate.

[0073] In this display device, a storing section configured by one or aplurality of storing circuits is provided at each of interconnectionslaid with a plurality of write lines and a plurality of data lines, tostore all the image signals required for on-screen display in eachstoring section. In the display control section, one or a plurality ofactive devices provided respectively connected to the storing circuitsof the storing section and current-driven luminescent devices havingareas corresponding to place values represented by image signals storedin the storing circuits controls the current to be supplied to thecurrent-driven luminescent devices on the basis of a value of the imagesignals (e.g. 0 or 1), thereby controlling light emission. These areintegrated on a semiconductor or insulating substrate, i.e. within eachdot array pattern.

[0074] Also, a display device according to the invention has saidcurrent-driven luminescent devices structured by EL devices.

[0075] In this display device, display is made by the EL devices as onekind of a current-drive luminescent device having the features ofreduced thickness, high definition, reduced power consumption, etc.

[0076] Also, a display device according to the invention has thecurrent-driven luminescent devices structured by organic EL devices.

[0077] In this display device, display is made by an organic EL deviceshaving the further features of inexpensive, low-temperature process andso on, besides the features of reduced thickness, high definition,reduced power consumption, etc. possessed by the EL devices.

[0078] Also, a display device according to the invention comprises; astoring section configured by one or a plurality of storing circuitsprovided at each of interconnections of a plurality of write lines and aplurality of data lines correspondingly to an array pattern of a dot asa minimum unit of display so that, when a write signal is transmittedthrough the write line and an image signal as a digital data signal forcontrolling display is transmitted through the data line, the imagesignal is stored; one or a plurality of active devices providedrespectively connected to the storing circuits of the storing sectionand liquid crystal driving sections having areas corresponding to placevalues represented by image signals stored in the storing circuits, adisplay control section provided in each dot to perform drive controlusing a liquid crystal on the basis of the values of the image signalsstored in the storing circuits, and these are arranged on asemiconductor or insulating substrate.

[0079] In this display device, a storing section configured by one or aplurality of storing circuits is provided at each of the each ofinterconnections laid with a plurality of write lines and a plurality ofdata lines, to store all the image signals required for on-screendisplay in each storing section. In the display control section, one ora plurality of active devices provided respectively connected to thestoring circuits of the storing section and liquid crystal drivesections, e.g. pixel electrodes, having areas corresponding to placevalues represented by image signals stored in the storing circuitscontrols the current to be supplied to the liquid crystal drive sectionson the basis of a value of the image signals (e.g. 0 or 1), therebycontrolling the brightness of display due to the liquid crystal. Theseare integrated on a semiconductor or insulating substrate, i.e. withineach dot array pattern.

[0080] Also, a display device according to the invention further lays aplurality of read lines correspondingly to the dot array pattern sothat, if a read signal is transmitted, the image signals stored in thestoring circuits are read out of the storing section.

[0081] In this display device, a plurality of read lines are laidcorrespondingly to the dot array pattern so that, if a read signal istransmitted, the image signals stored in the storing circuits are readout of the storing section thereby effecting data inputting andoutputting in the display device.

[0082] Also, a display device according to the invention comprises: adisplay drive section having a plurality of word lines, a plurality ofwrite lines and a plurality of data lines laid correspondingly to anarray pattern of a dot as a minimum unit of display, and a displaycontrol section operating, when at least a write signal is transmittedthrough the write lines and the image signals are transmitted throughthe data lines, on the basis of the storing section for storing theimage signals, the image signals and a word signal transmitted throughthe word lines, provided in each of the dot array patterns; a word linedriver section for controlling transmission of a word signal to the wordlines; a row decoder section for selecting a row for transmitting awrite signal to the write lines, to transmit the write signal to aselected row; a column decoder for selecting the data line; a columnselection switch section for transmitting the image signals as datasignals for controlling display to the data line selected by the columndecoder section; integrated and integrally formed on a semiconductor orinsulating substrate.

[0083] In this display device, a display drive section is laid with aplurality of word lines, a plurality of write lines and a plurality ofdata lines, and a display control section operating on the basis of thestoring section for storing the image signals, the image signals and aword signal transmitted through the word lines, that are provided ineach of the dot array patterns. Further, provided are a word line driversection for controlling transmission of a word signal to the word lines,a row decoder section for selecting a row for transmitting a writesignal to the word lines to transmit the write signal to a selected row,a column decoder for selecting the data line, a column selection switchsection for transmitting the image signals as data signals forcontrolling display to the data line selected by the column decodersection. These are integrated and integrally formed on a semiconductoror insulating substrate.

[0084] Also, in the display drive section of a display device accordingto the invention, a converting section for converting a value based onthe image signals stored in the storing section into an analog signal isprovided in each dot array pattern, and the display control sectionoperates on the basis of the analog signal and the word signal.

[0085] In this display device, in the display drive section, theconverting section is further provided between the storing section andthe display control section. Because the display control sectionoperates on the basis of the image signals, an analog signal, e.g. dueto pulse modulation, is generated.

[0086] Also, in a display device according to the invention, said wordlines are laid to transmit the word signal to the display controlsection on two rows.

[0087] In this display device, in order to reduce interconnections, theword lines as power supply lines are shared between the display controlsections, for example, on the upper and lower two rows, to transmit aword signal (supply power).

[0088] Also, the word line driver section and the row decoder section ina display device according to the invention are allocatedcorrespondingly to a length of the display drive section in a rowdirection, and the column decoder section and the column selectionswitch section are allocated correspondingly to a length of the displaydrive section in a column direction.

[0089] In this display device, in order to size-reduce the layout in anarea other than display, the word line driver section and the rowdecoder section are allocated correspondingly to a length of the displaydrive section in a column direction, and the row decoder section and thecolumn selection switch section are allocated correspondingly to alength of the display drive section in a column direction, therebyachieving space saving.

[0090] Also, each column selection switch structuring the columnselection switch of a display device according to the invention isallocated correspondingly to a width of the dot array pattern.

[0091] In this display device, each column selection switch is allocatedcorresponding to the width of the dot array pattern, in order to provideefficient layout.

[0092] Also, a display device according to the invention, said rowdecoder section selects a row for transmitting the write signal on thebasis of an address signal representing a storage position.

[0093] In this display device, in order to enable selection of anarbitrary row, the row decoder section selects a row for transmittingthe write signal on the basis of an address signal.

[0094] Also, the column decoder section of a display device according tothe invention selects the data lines on the basis of the address signal.

[0095] In this display device, in order to enable an arbitrary data line(column), the column decoder section transmits a data line on the basisof an address signal.

[0096] Also, in a display device according to the invention, three dotsfor developing and displaying in red, blue and green as light sourcecolors are provided as one pixel, the image signals are inputted on aone-pixel-unit basis, and the column decoder section selects data linesfor storing the image signals in an amount of one pixel.

[0097] In this display device, in color display, three dots fordeveloping and displaying in red, blue and green as light source colorsare provided as one pixel. The image signals are inputted on aone-pixel-unit basis as a reference of change of display. Also, thecolumn decoder section selects data lines for storing the image signalsin an amount of one pixel.

[0098] Also, in the display device according to the invention, thatthree dots for developing and displaying in red, blue and green as lightsource colors are provided as one pixel, the image signals are inputtedon a one-pixel-unit basis, and the column decoder section selects datalines for storing the image signals in an amount of a plurality ofpixels.

[0099] In this display device, in the case of performing color display,in order to reduce the clock frequency for use in storage, the imagesignals are inputted on a plurality-of-pixels-unit basis. The columndecoder section selects data lines in an amount of a plurality ofpixels.

[0100] Also, a display device according to the invention furthercomprises: a timing controller section for controlling at least timingof transmitting the address signal; a memory controller section forcontrolling transmission of the image signals; further integrated andintegrally formed on the substrate.

[0101] In this display device, the peripheral circuits required forcontrolling display are all systematically integrally formed on the samesubstrate.

Embodiments of the Invention

[0102] Next, preferred embodiments of the present invention will beexplained based on the drawings.

[0103] Embodiment 1

[0104]FIG. 1 is a block diagram representing a concept of a systemincluding a display device according to Embodiment 1 of the invention.FIG. 1 represents a concept called a system-on-panel (SOP). SOP is aconcept for integrally forming all the circuit systems concerned withdisplay, such as an active matrix, peripheral drive circuit, memoriesand controllers, on an insulating substrate, such as glass by the use ofpolycrystalline silicon TFTs or the like. For this reason, it ispossible to directly couple a panel to a CPU and hence to achieve costreduction, reliability improvement and space saving.

[0105] In FIG. 1, a digital interface 110 is configured with a CPU 110Ato transmit display data. Meanwhile, a panel 1 as a display device has adrive section configured by an active-matrix LCD section 2, a row driver3, a digital data driver 4, a memory controller 5 and a timingcontroller 6.

[0106]FIG. 2 is a diagram showing in detail a drive section of the panel1. The active-matrix LCD section 2 uses active devices, such as TFTs anddiodes, to effect display and stores pixel signals in one screen by theuse of a storage circuit section. The active-matrix LCD section 2 isarrayed with pixels in the number of i×j. The present invention, assumedon a color display, has light-source colors of R (red), G (green) and B(blue) three dots (called also as sub-pixels) of which configure onepixel. It is assumed herein that one dot represent one point, as aminimum unit, for effecting display. For a monochromatic display, onepixel equals to one dot.

[0107]FIG. 3 is a diagram representing an equivalent circuit configuredin each dot of the active-matrix LCD section 2. Each dot area includesdata lines, wordlines, active devices arranged at the intersections ofthem (e.g. switch devices by transistors, diodes or the like), DAC (e.g.a PWM waveform forming circuit) and storage circuits (e.g. latchcircuits). In the figure, 21 is a storage circuit section (storagesection) configured by one or a plurality of memory cells (storagecircuits). In the figure, four memory cells are provided. It is hereinassumed that each memory cell be static. Consequently, data can be heldwithout refresh at a constant time interval. Each memory cell, wheninputted with a Write signal, holds (stores) a binary signal (data)transmitted through d0, d1, d2 or d3. Herein, because four memory cellsare used for one dot, an information amount of 4 bits (value in 16combinations) can be held. Each dot can represent a brightness (tonallevel) based on that value. The number of the memory cells is in thesame as the number of a value k, hereinafter referred.

[0108]23 is a PWM waveform farming circuit (converting section). The PWMwaveform forming circuit 23 is a kind of a counter. This is so-called adigital/analog converter (DAC) for representing as a PWM waveform(analog data with a pulse width) a value represented by image signals onthe basis of the image signals (digital data) held by the storagecircuit section 21. In order to respond to an effective value of anapplied voltage, for tonal representation the LCD is required to converta data signal into an analog signal. Furthermore, in order to secure alifetime of liquid crystal, there is the need to apply an alternatingvoltage inverting at a constant time interval. For this reason, thepresent embodiment first converts digital data once into atime-base-modulated analog timing signal by the use of the PWM waveformforming circuit 23, and thereafter applies an alternating current drivevoltage VLC to the liquid crystal by the use of that timing signal.

[0109]22 is an active device section (display control section), forexample, of TFTs (thin film transistors). The conventional active devicehas connections between the drain (or source) and the data line andbetween the gate and the word line. In FIG. 3, the configuration is bydynamic devices. Meanwhile, the drain (or source) and the word line arein connection while the gate and the data line are in connection.Consequently, the active devices in the present embodiment do not switchby drive to the word lines but switches on the basis of values based onimage signals (pulse width due to PWM) to adjust the charge (current tobe supplied to the pixel electrodes) stored on the pixel electrodes (notshown). The pixel electrode forms a capacitance with a counter electrodethrough a liquid crystal (LC section 24). By a voltage applied betweenthe pixel electrode and the counter electrode, the optical rotatorypower due to liquid-crystal molecules is controlled to effect displaycontrol of the dots. Moreover, even if the switch of the active devicesection 22 is off (non-operation period), the pixel electrode is allowedto maintain its display state owing to built-up charge until refreshingin the next time (until rewriting display data). 24 is an LC section.The LC section 24 is a to-be-driven part actually not formed on theglass substrate. From the foregoing, storage drive control on each dotis implemented by signal transmission (current supply, voltageapplication) through the data lines (d1, d2, d3 and d4) and the wordlines (write). Also, display drive control is implemented by signaltransmission through the word lines (VLC and VCOM), PWMCLK and Set.Herein, VDD and VSS are provided to supply power to the storage circuitsection 21 and PWM waveform forming circuit 23. Meanwhile, the signallines of VDD, VSS, VLC, VCOM, PWMCLK and Set can be shared between tworows. This achieves layout simplification due to the reduction ofinterconnect lines, space saving, area increase of dot array patterns(opening-ratio increase).

[0110] In FIG. 2, it is a row driver 3 to control the drive to the wordlines. The row driver 3 is structured by a row decoder 31 and a wordline driver 32. The row decoder 31 selects and transmits a Write signalto a row of pixels for storing or rewriting (hereinafter, merelyreferred to as “store”) display data on the basis of input address data.

[0111]FIG. 4 is a diagram showing a relational example of VLC and VCONdrive waveforms. The word line driver 32 drives the VLC and VCOM.Because the LCD requires alternating drive, at least the VLC rust bemade in the form of an alternating current. FIG. 4(a) is a waveform whenVLC=VCOM±Va is given. Where the relationship between VLC and VCOM isgiven as in FIG. 4(a), consumption current can be reduced because COM issatisfactorily constant. Due to this, as the smaller the display area(the number of pixels), the greater the power reduction can be achieved.This accordingly is suited for a reflective LCD used for displayingcharacters (letters, symbols, etc.). Also, because VCOM to be suppliedcommonly to all the rows is constant regardless of time, each VLC can bedriven (scanned) with phase deviation. It is noted that, in this case,there is increase in the number of power sources and complication incircuit configuration.

[0112] On the other hand, FIG. 4(b) is a waveform when driving is madesuch that VLC and VCOM are alternating-current inversion with oppositephase. In this case, it is possible to reduce the number of paversources and simplify the circuit structure. However, because VCOM itselfchanges in potential without causing display, power is consumed by thecapacitance between the interconnections and the VCOM. Accordingly,there is increase in consumption power by VCOM regardless of displayarea broadness. Meanwhile, VCOM is common to all the rows as mentionedbefore. Accordingly, because all of the VLC must be driven on the basisof the phase of VCOM, each of VLC cannot be driven (scanned) with phasedeviation.

[0113] On the other hand, it is a digital data driver 4 that drives thedata lines. The digital data driver 4 is configured with a columndecoder 41, an input control circuit 42 and a column selection switchsection 43. The column decoder 41 selects a column having the pixels tobe stored (rewritten) with display data from among the columns (in thenumber of j) on one row (line) on the basis of input address data. Thisselects data lines to be driven. The input control circuit 42 is acircuit for controlling one pixel of image signals (k×3)parallel-transmitted from the memory controller 5. As described before,the value of k and the number of memory cells in the storage circuitsection 21 are the same, which is the number required to represent thedots at a brightness with tonal levels of 2^(k). Consequently, k=4 isgiven in FIG. 2, wherein 16 tonal levels of brightness are to be set oneach dot. The column selection switch section 43 is providedcorrespondingly to the number of pixels (that is, k×3×j) on one line onthe basis of image signals (k×3) per pixel as a unit. Each columnselection switch switches on the basis of the selection by the columndecoder 41 and image signals to transmit image signals onto (drive) thedata lines. The column selection switch is configured for arrangementcorrespondingly to a width nearly the same as a width of the dot.Accordingly, the column selection switch section 43 will not be longerin width than the active matrix LCD section 2, and can be ideally laidout in view of interconnections.

[0114] The memory controller 5 controls as image signals of k×3 thedisplay data transmitted from the CPU 110A. Also, the timing controller6 has at least an address buffer 61 and a PWM taming signal generatingcircuit 62, to transmit an address signal to the row decoder 31 andcolumn decoder 41 in order to store the display data transmitted fromthe CPU 110A. Also, transmitted is a timing signal for generating PWMCLKto the PWM timing signal generating circuit 62. The PWM timing signalgenerating circuit 62 generates a PWMCLK as a reference for forming aPWM waveform in the PWM waveform forming circuit 23 on the basis of thetiming signal. Also, selected are Set lines to transmit a Set signal.

[0115] It is the active-matrix LCD section 2 as an actual display partthat occupies the greatest area in the glass substrate (panel).Moreover, its size is fixed. Accordingly, it is the problem in the SOPwith what efficiency the systems, such as peripheral circuits, are laidout in portions other than the active-matrix LCD section 2 and whetherintegration density is to be increased for realization of such layout.Furthermore, it is possible to take a way of thinking of effectivelyutilizing the size-fixed active-matrix LCD section 2. For this reason,the present embodiment forms within each dot the memory cells and DACsrequired for displaying the dot at a certain tonal level, thus achievingextreme space saving. That is, the pixel array and the memory array aremade the same to eliminate the necessity of providing, outside theactive-matrix LCD section 2, a space for providing the memory cells forstorage of one screen of display data. Moreover, one screen of data canbe all stored because of the storage circuits in each dot. For thereason, the data exchange with the CPU 110A is reduced to achieve alsothe reduction in consumption power by exchanging only the display datafor the pixels to be changed of display (rewritten of display data).However, there is a possibility that the area occupied by circuitswithin the dot increases as compared to the conventional case of formingTFTs only. Consequently, with a scheme of light transmission from thebackside by a backlight, there is a possibility of increasing theopening ratio to decrease the transmissivity. Accordingly, it is to beconsidered that the present embodiment is suited for a reflective LCD.

[0116]FIG. 5 is a figure representing drive waveform examples of thesignals inputted by the row driver 3 and digital data driver 4. Based onthe figure, explanation is made on the storage operation and displayoperation in the present embodiment. First explained is the displayoperation. Herein, four rows are taken as one group to control theoperation of display. It is assumed herein that VLC assumably have oneperiod comprising 40 periods of PWMCLK (refresh interval of 20 periodsof PWMCLK). This varies depending on the PWMCLK required respectivelyfor display operation and storage operation.

[0117] Inputted with a Set signal, the PWM waveform forming circuit 23generates a pulse waveform having a width based on the PWMCLK and imagesignal stored in the storage circuit section 21. In FIG. 5, each of datarepresents a relationship between a value represented by each imagesignal stored in the storage circuit section 21 and a PWM waveform.Provided that the value due to the image signals stored in four memorycalls is “0000”, the conversion by the PWM waveform forming circuit 23is into a pulse width of one PWMCLK waveform. Also, with “0001”, theconversion by the PWM waveform forming circuit 23 is into a pulse widthof two PWMCLK waveforms. Similarly, with “0010” the conversion is forthree PWMCLK waveforms, and with “0011” the conversion is for fourPWMCLK waveforms. Finally, with a value “1111” the conversion is forsixteen PWMCLK waveforms. Because the conversion herein is with the4-bit value, conversion is possible with 16 periods of PWMCLK. However,the PWMCLK required for display operation varies depending upon a rangeof value of conversion.

[0118] The LCD, requiring alternating-current drive, needs to be drivenwhile refreshing all the pixels at least at a certain frequency. It isnoted that the pixels not to be driven, i.e. the off-state pixels, donot require refresh because no voltage is satisfactorily appliedthereto. Herein, although consumption power reduction can be achieved bylowering the frequency, flicker occurs due to punch-through voltage orthe like. In order to make flicker not conspicuous while achievingconsumption power reduction, for a still picture the PWMCLK is set toeffect refresh at a frequency of minimally 30 Hz (liquid crystal is15-Hz driven) thus maintaining a display state. Heroin, driving is madeby inversion of the phase on first and second rows of VLC in one groupand the phase on third and fourth rows of VLC, in order to furthersuppress flicker. By thus always displaying nearly halves of the screenin different phases, the transmissivity difference due to polaritydifference is averaged making flicker not conspicuous. Although thefirst, second row and the third, fourth row are inverted, this in notlimited to.

[0119] In FIG. 5, because a Set signal in the next group is inputtedafter about two periods of PWMCLK, the VLC phases in the next groupdeviate by the corresponding amount (however, the VLC phases inputted to40-44th rows again become same). It is of importance herein that thereis a need to make same the rise of VLC and the rise of PWMCLK . Displayoperation is implemented by operating the PWMCLK, set, VLC and VCOM inthe above timing.

[0120] Next, storage operation will be explained. Although the VLC has aperiod comprising 40 periods of PWMCLK (refresh interval of 20 periodsof PWMCLK), the PWM waveform forming circuit 23 operates only in time of16 periods of PWMCLK. Accordingly, the retaining portion is given as anon-operative period of the PWM waveform forming circuit 23 (this periodtaken T1). Storage operation is made within the non-operative period T1.Although herein T1 is set an 4 periods of PWMCLK, the value T1 isadjusted in a range for storage operation.

[0121] In FIG. 5, Write signals are inputted at an interval of a halfperiod of PWMCLK. It is assumed that, if one Write signal is inputted,display data be stored to a certain row. With the configuration of FIG.1, one pixel of image signals (k×3) only is inputted per time to theinput control circuit 2, and one pixel of rows only can be selected pertime by the column decoder 41. Consequently, despite made for the row,there is no change in one-row display data simultaneously with the inputof a Write signal.

[0122] Meanwhile, although in FIG. 5 the Write signal is driven insynchronism with PWMCLK, there is no especial necessity of suchsynchronism. The importance lies only in that the storage operation tothe storage circuit section 21 must be carried out within thenon-operative period T1 of the PWM waveform forming circuit 23.Accordingly, it is also possible for the column decoder 41 to scan andselect each column for storage during inputting the Write signal.

[0123] Furthermore, if there are allowances available, storage operationcan be also made to all the dots (pixels) that the PWM waveform formingcircuit 23 is out of operation. In this case, however, there is increasein clock frequency required for storage operation. For this reason, byutilizing arbitrary designation of an address signal of the timingcontroller 6 on a pixel-by-pixel basis and static circuits of memorycells, only the pixels to be rewritten may be selected and rewrittenduring the non-operative period T1. In this case, the CPU 110Asatisfactorily transmits only the display data to be stored (changed indisplay). In this case, it is assured that the number of the pixelsrequiring storage operation be equal to or less than the number ofpixels to be scanned for storage operation. Consequently, the clockfrequency required for storage operation can be suppressed and theexchange with the CPU 110A be lessened. For power reduction, it is themost effective to carry out storage operation by this method.

[0124] Herein as for the storage circuit section 21, although the memorycells if configured by static memories dos not require data rewriting(refresh), they if configured by dynamic memories require refresh insuch timing as can hold storage.

[0125] According to the first embodiment as above, the portionsincluding the peripheral circuit besides the display section areintegrally formed as systems on a glass substrate, and further thestorage circuit section 21 (memory cells) and PWM waveform formingcircuit 23 (DAC) required for causing the dots at certain tonal levelsis formed matched to a dot-array pattern. Accordingly, there are no needto newly lay out and design these circuits in an area other than theactive-matrix LCD section 2. The systems can be formed on a panel (glasssubstrate) and further extreme space saving be achieved. Moreover,because each dot possesses a storage circuit section 21, the displaydata in amount of one screen can be all stored.

[0126] Consequently, even if only the image signal in amount of displaydata for the pixels to be rewritten be transmitted from the CPU 110A, itcan be stored in the storage circuit section 21 corresponding to thepixels. Because the row decoder 31 and the column decoder 41 can selecton a pixel unit basis, the system overall is reduced in datatransmission amount and hence in consumption power. Furthermore, becausethe memory controller 5 and the timing controller 6 are also integrallyformed on the panel 1, the panel 1 can be directly coupled to the CPU110A thus making the system overall low in cost, high in reliability andlean in space.

[0127] Embodiment 2

[0128]FIG. 6 is a diagram representing in detail a drive section of apanel 1A according to a second embodiment of the invention. In thefigure, those denoted with the same reference numerals as in FIG. 2operate in the same way, hence the explanations thereof being omitted.In the figure, 2A is an active-matrix OELD (Organic ElectroLuminescentDisplays) section. The active-matrix OELD section 2A employs an OELluminescent section 25 in place of the LC section 24 of theactive-matrix LCD section 2. The OEL luminescent section 25 isconstituted with OEL devices. The OEL device signifies organic ELdevices (Organic ElectroLuminescent devices). The OEL device in one ofcurrent-driven electroluminescent devices. This current-drivenelectroluminescent device is a spontaneous luminescent device whichemits light upon supply of electric current unlike a liquid crystal. TheEL devices including organic and inorganic ones among suchcurrent-driven luminescent devices have the following features and areexpected in the field of displays and the other fields. The OEL deviceis cheap in material and enhanced in electro-optical conversionefficiency by research and development, thus achieved in power reductionfurthermore.

[0129] (1) wide viewing angle

[0130] (2) weight and thickness reduction possible

[0131] (3) high contrast ratio

[0132] (4) low consumption power (backlight not needed)

[0133] (5) various optical characteristics (hue degree, spectralcharacteristics, brightness, etc.) realized by molecular design ofmaterial.

[0134] (6) high definition display possible owing to current drive.

[0135]FIG. 7 is a diagram representing an equivalent circuit configuredin each dot of the active-Matrix OELD section 2A. In FIG. 7, thosedenoted with the same reference numerals an in FIG. 3 operates similarlyto the explanation in the first embodiment, hence the explanationsthereof being omitted. In the figure, 22A is an active device sectionsimilar to the active device section 22. In FIG. 7, p-channel TFTs areused. The OEL device is satisfactorily driven on direct current (DC) andhence structurally made simpler than the active device for drivingliquid crystal. Furthermore, the number of interconnections can belessened because one word line for VOEL is satisfactorily provided inplace of providing two (VLC, VCOM) word lines as in the LCD. 25 is anOEL luminescent section mentioned before. In this embodiment, similarlyto the first embodiment, the display operation by the panel formed bythe concept of SOP is implemented by emitting the OEL devices instead ofdoing on the optical rotatory power of liquid crystal.

[0136] Next, explanation will be made on the operation of the presentembodiment. The present embodiment is basically not different inoperation from the first embodiment. However, the active device section22A must be operated on negative logic because of the p-channel TFTs.Consequently, the waveforms the PWM waveform forming circuit 23 convertsbased on the image signal are reverse in polarity to those of FIG. 5.Also, the OEL devices, because of satisfactorily driven on directcurrent, usually do not require refresh with inversion driving (however,the active device section 22A of FIG. 7 because of dynamic devicesrequires the supply of current to maintain display).

[0137] According to the second embodiment as above, in a display devicehaving a panel 1A that the portion including the peripheral circuits isintegrally formed as systems over a glass substrate and further thestorage circuit section 21 and PWM waveform forming circuit 23 requiredfor causing the dot at certain tonal levels are formed within each dot,display is made using current-driven luminescent devices that emit lightby current supply instead of using the drive to liquid crystal thusachieving high-definition display and the like. Moreover, backlight isnot required hence achieving power reduction. In particular, the presentembodiment implementing display by emitting the OEL devices among the ELdevices of the current-driven luminescent devices has features of the ELdevices of thin film devices formed over a large-sized glass substrateand achieving thickness reduction and size increase, capacity increase(high definition on the dot matrix) and full color. Furthermore, cost isreduced because of inexpensive material and power is reduced furthermoreowing to high electro-optical conversion efficiency. Moreover, becausethe active-matrix OELD section 2A is OELD of the active-matrix type,drive voltage can be largely reduced as compared to the simple-matrixtype display. The use of efficient operation points achieves furtherpower reduction. Furthermore, because the EL devices are thin-filmdevices, space saving and thickness reduction are achieved (without thenecessity of using two glass substrates for sandwich as in the liquidcrystal) in case the system overall is integrally formed based on SOP.The OEL-device manufacture process can be implemented by alow-temperature process as compared to the TFT manufacture processessential for the active-matrix type. Accordingly, even if added is anOEL-device forming process after integrally forming the circuitsincluding TFTs on a glass substrate, there is no affection on the TFTshence convenient in view of the consideration from the various pointssuch as process and yield. For the LCD the interconnection must be madeby providing two word lines (VLC and VCOM) for specifying the rove fordisplay, whereas for OELD such word line (VOEL) is satisfactorily one inthe number. The further decrease in the number of interconnectionsachieves layout simplification, space saving, dot-array-pattern areaincrease (increased opening ratio) and so on. Furthermore, the use ofthe OEL devices in the saturation area allows for current supply withoutthe substantial affection from deviation in threshold levels of theactive devices between the dots.

[0138] Embodiment 3

[0139]FIG. 8 represents the waveforms in one period of the PWMCLK of thethird embodiment. In the first and second embodiments, the PWM timingsignal generating circuit 62 generated PWMCLK with the same pulse width(same period). This embodiment generates a generation pulse width ofPWMCLK on the basis of a function based, for example, upon γ-correction.A PWM timing signal generating circuit 62A in provided as a circuit forthat purpose. Herein, γ-correction is meant, in nature, to correct therelationship of an exponential function called γ-characteristic, such asD=E^(γ), existing between an input quantity of light E and an outputvalue D in a CCD camera or the like. In the LCD or OELD, however, thereis also a meaning of correction for providing visually natural tonalrepresentation to the relationship between a value represented by imagesignals in amount of one dot and a brightness. In this embodiment, thelatter meaning is principally used wherein the current for supply to theOEL devices is controlled meeting a γ-characteristic.

[0140] For this reason, the PWM timing signal generating circuit 62Agenerates a generation pulse width of PWMCLK on the basis of aγ-characteristic exponential function. Then, the PWM waveform formingcircuit 23 generates a PWM waveforms that the value represented by animage signal is converted based on the PWMCLK generation pulse width.The current to be supplied to the pixel electrode or OEL device iscontrolled by giving a switching time to the active device section 22 oractive device section 22A on the basis of the PWM waveform. The PWMCLKif generated with the same interval of pulse width allows fortransmission of set signals in the next group two-pulse after the PWMCLKas in FIG. 4. Herein, the difference from the operation of the first orsecond embodiment lies in that, because the PWMCLK pulse width variesand the variation provides a period, there is a need of transmitting setsignals in a manner matched to this period.

[0141] According to the third embodiment as above, the PWMCLK pulsewidth is set based on a γ-characteristic exponential function to providethe switching time by the active device section on the basis of a PWMwaveform generated matched to the PWMCLK, thereby enabling currentsupply to the pixel electrodes or OEL devices on the basis ofγ-correction. Due to this, the relationship between a display data value(value based on the image signal) and a tonal level (brightness) can berepresented linearly.

[0142] Embodiment 4

[0143]FIG. 9 is a diagram representing in detail a drive section of apanel 13 according to a fourth embodiment of the invention. In thefigure, those denoted with the same reference numerals as in FIG. 2operate the same as in FIG. 2, hence explanations thereof being omitted.43A is a column selection switch section which operates similarly to thecolumn selection switch section 43 as explained in the first embodiment.The present embodiment, because of k=6 given, is different only in thatthe column selection switches are provided in the corresponding number.Also, the timing controller 6A operates basically similarly to thetiming controller 6. However, this embodiment is different in that notiming signal is transmitted because of absence of a PWM timing signalgenerating circuit 62.

[0144]FIG. 10 is a diagram representing an equivalent circuit configuredin each dot of the active matrix OELD section 2B. In FIG. 10, 21A is astorage circuit section. The different point from the first and secondembodiment lies in that six memory cells are provided correspondingly tok=6. Meanwhile, 22B is an active device section similar to the activedevice section 22A. However, the active device section 22B is differentfrom the active device section 22A in that the active devices directlyconnected to the memory cells are provided in the number of the memorycells (six in FIG. 10). 25A is an OEL luminescent section. In FIG. 10,six OEL devices are connected to the respective active devices. Herein,actually each OEL device has an area corresponding to the value(2^(k−1)) represented by an image signal on each memory cell connected,wherein the area ratio is given as S1:S2:S3:S4:S5:S6=1:2:4:8:16:32.These are set to emit light at a brightness corresponding to the area.

[0145] The present embodiment is caused to emit light by combining theOEL devices different in area connected to the respective memory cellsand active devices, thereby representing a tonal level of each dot bythe luminescent area. The circuit is intended for simplification withoutthe provision of the DAC (PWM waveform forming circuit 23) in each dotas provided in the second embodiment. Space saving is made by simplifiedinterconnections and omitted peripheral circuits without the provisionof PWMCLK and Set signal lines and a PWM timing signal generatingcircuit 62 for transmitting such signals.

[0146] Next, the operation of the present embodiment will be explainedbased on FIG. 9 and FIG. 10. As for storage operation, operation is madesimilarly to the explanation in the first embodiment. Using displaynon-operative period T1, image signals representing a value 2^(k−1)(k=1-6) are respectively inputted to d5, d4, d3, d2, d1 and d0.

[0147] Next, the operation of display will he explained. On the basis ofthe image signals stored on the memory calls of the storage circuitsection 21A, switching operation is made in each active device of theactive device section 22B. It is herein assumed that the switch be in anon state by the active device if the image signal represents “1” whilethe switch be in an off state if it represents “0”. The word line driver32 drives VOEL. This supplies current to the OEL device connected to anactive device whose switch is on. Although display operation can be madeby always driving VOEL on all the rows, there is a need of providing anon-operative period T1 in order for storage operation. Because there isa possibility of causing flicker if the non-operative period T1 is giventhe same for the rows, it is preferred to deviate the non-operativeperiod T1 between the rows. The timing is given by adjusting the VOELdrive by the word line driver 32.

[0148] According to the fourth embodiment as above, the devices of theactive device section 22B and OEL luminescent section 25A are connectedcorrespondingly to the memory cells of the storage circuit section 21A,so that the place value represented by an image signal of each memorycell is placed corresponding to the OEL device area connected to eachmemory cell. On the basis of an input image signal, OEL luminescence iscontrolled to control the luminescent area, thereby representing a tonallevel on each dot. Accordingly, circuit simplification in achievedwithout the provision of the DAC on a dot-by-dot basis. Due to this,because there is no need of providing the signal lines, such as forPWMCLK and Set, and PWM timing signal generating circuit 62 fortransmitting such signals, space saving is achieved by simplifiedinterconnections and omitted peripheral circuits. Furthermore, asmentioned before, the use of the OEL devices in a saturation regionmakes possible to supply current without substantial influence of athreshold level of the active device section 22B in each dot.

[0149] Embodiment 5

[0150]FIG. 11 is a diagram representing in detail a drive section of apanel 1C according to a fifth embodiment of the invention. In thefigure, those denoted with the same reference numerals as in FIG. 9operate similarly to FIG. 9, hence explanations thereof being omitted.This embodiment is given k=4 and has a column selection switch 43Bcorrespondingly to that. Meanwhile, an active matrix LCD section 2C isprovided in place of the active matrix OELD section 2B.

[0151]FIG. 12 is a diagram representing an equivalent circuit configuredin each dot of the active-matrix LCD section 2C. In FIG. 12, 22C isactive-matrix device sections provided in the number of memory cells(four in FIG. 12) The active device is configured, for example, with twoN-channel TFTs or the like. One active device 22Ca has a gate to beinputted by an output of the memory cell while the other active device22Cb has a gate to be inputted by an inverted output of the memory cell.The memory cell (storage circuit 21) is configured by a static memorycall as represented by one or a plurality of latch circuits, similarlyto the above embodiments. The storage data of the memory circuit 21 issupplied to the gate of the active device 22Ca while the inversion datato the storage data of the memory circuit 21 is supplied to the gate ofthe active device 22Cb.

[0152] Meanwhile, 24A is LC sections provided in the number of thememory cells (four in FIG. 12). These LC sections 24A are respectivelyinterposed between counter electrodes and active device sections 22C,and connected to a drain (source) side of the active devices 22Ca and22Cb.

[0153] The source (or drain) side of the active device 22Ca to besupplied by an output of the memory cell is connected to a signal lineof an alternating-current signal VLCON inverting at a predetermined timeinterval while the source (or drain) aide of the active device 22Cb tobe supplied by an inverted output of the memory call is connected to asignal line of a direct-current signal VLCOFF having a potential VCOM ofthe counter electrode.

[0154] The alternating-current signal VLCON, as shown in FIG. 13, is asignal inverting at a predetermined time interval with reference to thecounter electrode potential VCOM as a reference, and is analternating-current voltage capable of turning on the LC section 24A.Meanwhile, the direct-current signal VLCOFF is a direct-current voltagecapable of turning off the LC section 24A. These alternating-currentsignal VLCON and direct-current VLOFF are generated in the word linedriver 32.

[0155] The pixel electrodes, not shown, of the LC section 24A have areasdifferent from one another. Provided for example that in FIG. 12 thepixel electrode of an LC section 24A has an area of S1, S2, S3 or S4 inthe order from the right, the area ratio is given S1:S2:S3:S4=1:2:4:8.

[0156] The present embodiment has a combination of a plurality of LCsections 24A having pixel electrodes different in area to apply the samevoltage to between the pixel electrodes and the counter electrode,thereby representing a tonal level on each dot caused by the differenceof brightness due to the difference of area. Similarly to the fourthembodiment, circuit simplification is intended without the provision ofthe DAC (PWM waveform forming circuit 23) on each dot as was provided inthe first embodiment. Also, space saving is achieved by simplifiedinterconnection and omitted peripheral circuits without the provision ofPWMCLK and Set signal lines and a PWM timing signal generating circuit62 for transmitting such signals.

[0157] Next, the operation of this embodiment will be explained based onFIG. 12. As for storage operation, operation is made similarly to theexplanation in the first embodiment. Using display non-operative periodT1, image signals representing a value 2^(k−1)(k=1-4) are respectivelyinputted to, d3, d2, d1 and d0.

[0158] Next, the operation of display will be explained. On the basis ofthe image signals stored on the memory cells of the storage circuitsection 21, switching operation is made in each active device of theactive device section 22C. It is herein assumed that the active device22Ca be in a switched-on state and the active device 22Cb be in aswitched-off state if the image signal represents “1” while the activedevice 22Ca is in an off state and the active device 22Cb be in an onstate if it represents “0”. The word line driver 32 outputs analternating-current signal VLCON inverting with a predetermined periodand a direct-current signal VLCON having a counter electrode potentialVCOM. Due to this, where the image signal is “1”, the active device 22Cais switched on and the active device 22Cb is switched off therebyapplying an alternating-current signal VLCON to the pixel electrodes ofthe LC sections 24A

[0159] Conversely, where the image signal is “0”, the active device 22Cais switched off and the active device 22Cb is switched on therebyapplying a direct-current signal VLOFF, i.e. counter electrode potentialVCOM, to the LC sections 24A.

[0160] In this case, because the areas of the pixel electrodes are setto have an area ratio of 1:2:4:8, even where the same potential isapplied, brightness is given different for each of the LS sections 24Athus effecting tonal representation.

[0161] According to the fifth embodiment as above, the active devicesection 22C and LC sections 24A different in pixel-electrode area areconnected correspondingly to the memory cells of the memory circuitsection 21 so that the brightness on the LC sections 24A is controlledat the basis of the input image signal thereby representing a tonallevel on each dot. Accordingly, circuit simplification is achievedwithout the provision of the DAC on a dot-by-dot basis, thus achievingspace saving similarly to the fourth embodiment.

[0162] Meanwhile, in this case, because the counter electrode potentialVCOM is applied an a direct-current signal VLCOFF, circuitsimplification is achieved without newly providing a power source forthe direct-current signal VLCOFF.

[0163] Also, in the fifth embodiment, the signal lines VDD, VSS, VLCONand VLCOFF can be shared between two rows, thus achieving layoutsimplification owing to decrease in the number of interconnections,space saving, dot-array pattern area increase (opening ratio increase)and so on.

[0164] Embodiment 6

[0165]FIG. 14 is a diagram showing an equivalent circuit configured ineach dot in a sixth embodiment of the invention. In FIG. 14, thosedenoted with the same reference numerals as in FIG. 7 operate similarlyto FIG. 7, hence explanation thereof being omitted. 21B is a storagecircuit section. The difference from the storage circuit section 21explained in the first embodiment lies in that the image signal storedis to be read out. Accordingly, the image signal is hot only stored fordisplay but can be used for such an application of exchanging displaydata with the CPU 110A, for example.

[0166] It is needless to say that the timing of reading display data outof the storage circuit section 21B cannot be simultaneous with Write(storage) and Read (reading out of display data) of display data.Because the data lines are commonly used for Write and Read (same routein reading and storage) from the structural relationship, Read is notallowed even during Write to another pixel. From the above, when Writeis not being done to a certain pixel, Read is possible. Moreover,because synchronization with display timing is not especially made,reading out may be made during a display-operation period even within arange having no affect upon display.

[0167] According to the sixth embodiment as above, display data (imagesignal) is to be read out of the storage circuit section 21B thus beingused for other applications. Despite the reading rate is lower ascompared to the usual memory, as concerned with display data it ispossible to reduce the storage circuits (memories) in respect of cost,occupation area and the like.

[0168] Incidentally, although in the sixth embodiment explanation wasmade on the case that display data is to be read out of the storagecircuit section 21B in the second embodiment shown in FIG. 7,application is possible to the storage circuit section 21 in the fifthembodiment shown in FIG. 12. In this case, the storage circuit section21 may be configured such that the image signal stored can be read outsimilarly to the sixth embodiment. This makes it possible to obtain theoperation and effect equivalent to the sixth embodiment.

[0169] Embodiment 7

[0170] Although the above embodiment had one pixel to be selected in onetime by the column decoder 41, the invention is not limited to this.Pixels in plurality are configured to provide each set, and the columndecoder 41 is provided to select the data lines on a set-by-set basis.Furthermore, the number of display data to be inputted to the inputcontrol circuit 42 is matched to them (for twice, k×2×3 image signals)thereby enabling input-control the display data for the set at one time.With such a configuration, the display data in plurality can be dealtwith at one time. Despite interconnections are increased, the clockfrequency required for storage can be lowered than that in the case ofstorage on a pixel-by-pixel basis. Thus, power consumption can bereduced.

Effect of the Invention

[0171] As described above, in order to control on-screen display, thisdisplay device has, in each dot, a storage section for storing a signaland a display control section for controlling on-screen display on thebasis of the signal stored by the storing section. These are integratedon a semiconductor or insulating substrata, i.e. within each dot arraypattern. Accordingly, it is possible to decrease the circuits to beconfigured in an area other than the display region and to achieve spacesaving.

[0172] Also, this display device has, in each dot, a storing sectionconfigured by one or a plurality of storing circuits for storing imagesignals as digital data signals, a converting section for converting avalue based on the image signals into an analog signal, and a displaycontrol section for performing tonal control using a liquid crystal onthe basis of the analog signal. These are integrated on a semiconductoror insulating substrate, i.e. within each dot array pattern.Accordingly, the integration matched to a display region eliminates thenecessity of laying out them outside the display region, thus achievingspace saving. This invention is effective particularly for thereflective liquid crystal display device in view of the problem withtransmissivity. Also, because the storing section is provided in eachdot to store all the signals required for on-screen display, signalexchange can be decreased. This achieves the reduction of consumptionpower.

[0173] Also, in this display device, the storing circuit is configuredby a static circuit, thereby achieving image-signal holding over a longterm as compared to a dynamic circuit. Accordingly, despite the numberof devices increases, there is no necessity of changing storage in theportions display is not to be changed. This decreases exchange of imagesignals, thus achieving power reduction.

[0174] Also, in this display device, because the converting sectionperforms pulse width modulation in converting a value based on the imagesignals into an analog signal, the image signal can be efficientlyconverted into an analog signal.

[0175] Also, in this display device, because the converting sectionperforms pulse width modulation based on a γ-characteristic inconverting a value based on the image signals into an analog signal, therelationship between a value based on the image signals and a brightnesscan be linearly expressed.

[0176] Also, in this display device, the converting section performsconversion into the analog signal with a predetermined period.Accordingly, where display control is made, for example, by a liquidcrystal, it is convenient for cases requiring refresh at a constant timeinterval.

[0177] Also, in this display device, provided is a duration that noconversion into an analog signal is made in a duration of the constantperiod. Accordingly, in this duration, it is possible to change theimage signals to the storing section. Thus stabilization of display isachieved.

[0178] Also, in this display device, a start time of the constant periodis different between converting sections, and the duration no conversioninto an analog signal is made is made different. Non-operative durationcan be made different and flicker can be suppressed.

[0179] Also, in this display device, because an alternating currentdrive voltage is applied, lifetime can be increased even whereperforming display using a liquid crystal.

[0180] Also, in this display device, a voltage driven at VCOM±Va withrespect to a reference voltage VCOM is provided as an alternatingcurrent drive voltage, power consumption can be suppressed. Moreover,because the reference voltage is constant on any of the rows, scanningis possible.

[0181] Also, in this display device, because a voltagealternating-current-inversion-driven by two voltage-applying lines laidcorrespondingly to the dot array pattern is provided as an alternatingcurrent drive voltage, the configuration of the circuit to be driven canbe simplified.

[0182] Also, in this display device, because an alternating currentdrive voltage opposite in phase on the rows in pair is applied, flickercan be suppressed. Also, on the rows in pair, the lines to be applied bythe voltage can be shared.

[0183] Also, in this display device, current-driven luminescent devicesare connected to the display control section so that the emitted lightthereof is controlled on the basis of the analog signal therebyachieving tonal control. Accordingly, space saving is possible.Moreover, power reduction can be achieved by the use of thecurrent-driven luminescent devices. In addition, the use of thecurrent-driven luminescent device in a saturated region makes possibledisplay without substantial influence of variation of operationalcondition possessed by the display control section.

[0184] Also, in this display device, one or a plurality of storingcircuits, active devices and current-driven luminescent devices arecorrespondingly connected, wherein each current-driven luminescentdevice is given an area corresponding to place values represented by theimage signals connected, enabling tonal display due to the area.Accordingly, tonal control directly using the image signals is possiblewithout providing such a circuit as the converting section. Furthermore,the use of the current-driven luminescent device in a saturation regionmakes possible display without suffering substantial influence ofvariation in operational condition possessed by the display controlsection.

[0185] Also, in this display device, because display is made by the ELdevices, display is possible with high definition, reduced thickness andincreased area, increased capacity or the like. Also, because there isno necessity of using backlight as in the transmissive LCD, consumptionpower reduction can be achieved.

[0186] Also, in this display device, because display is made by organicEL devices, material in inexpensive and further electro-opticalconversion efficiency is high thereby achieving further power reductionbesides the capability of displaying with high definition as by the ELdevices. Also, because there is no need of using backlight as in thetransmissive LCD, power consumption reduction can be achieved.

[0187] Also, in this display device, one or a plurality of storingcircuit, active devices and a liquid crystal are correspondinglyconnected, to provide a liquid crystal drive section for driving eachliquid crystal with an area corresponding to a value of a placerepresented by the image signal connected, thereby enabling tonaldisplay due to the area. Tonal control directly using image signals canbe made without providing such a circuit as the converting section.

[0188] Also, in this display device, because the image signals stored inthe storing circuits can be readout, the display device can operate asstoring means. Consequently, the storing means can be saved.

[0189] Also, in this display device, integrated on a semiconductor orinsulating substrate are a display drive section having a storingsection and a display control section in each dot array pattern, a wordline driver section for controlling transmission of a word signal, a rowdecoder section for transmitting a write signal to a selected row, acolumn decoder section for selecting data lines and a column selectionswitch section for transmitting the image signal by switching operation.Accordingly, besides the display portion, the portions includingperipheral circuits are all integrally formed without using a chip orthe like. Moreover, because the storing section is provided within eachdot array pattern, there is no necessity of laying out outside thedisplay region, thereby further achieving extreme space saving.

[0190] Also, in this display device, because in the display drivesection the converting section for converting the image signals into ananalog signal in provided within the dot array pattern, further spacesaving can be achieved.

[0191] Also, in this display device, because the word lines are sharedby the display control section on two rows to transmit a word signal(supply power), interconnection can be reduced thereby achieving layoutsimplification, space saving, opening ratio increase and so on.

[0192] Also, in this display device, the word line driver section andthe row decoder section are allocated corresponding to a length of thedisplay drive section in a row direction and the column decoder sectionand the column selection switch section are allocated corresponding to alength of the display drive section in a column direction. Accordingly,the layout other than the display region can be reduced in size as smallas possible, thus achieving space saving.

[0193] Also, in this display device, because each column selectionswitch is allocated corresponding to a width of the dot array pattern,efficient layout can be made.

[0194] Also, in this display device, because the row decoder sectionselects a row for transmitting a write signal on the basis of an addresssignal, selection with high freedom can be made in selecting a row to bechanged.

[0195] Also, in this display device, selection with high freedom can bemade by selecting data lines on the basis of the address signal by thecolumn decoder section.

[0196] Also, in this display device, because the column decoder sectionselects the data lines for storing the image signal in an amount of onepixel, inputting is possible on a one-pixel-unit basis as a reference ofdisplay change.

[0197] Also, in this display device, where performing color display,image signals are inputted on a plurality-of-pixels basis and the columndecoder section selects data lines in an amount of a plurality of pixelson the basis of that input. Accordingly, despite the interconnectionsare complicated, the clock frequency used for storage can be loweredthereby achieving consumption power reduction. Also, even if the activedevices inferior in characteristic to single-crystal TFTs are operatedas the display control section, sufficient operation is obtained.

[0198] Furthermore, in this display device, because the peripheralcircuits required for controlling display are all systematicallyintegrally formed on the same substrate, the system entirety can bereduced in cost, improved in reliability and saved in space.

1. A display device, characterized by comprising: a storing section forstoring a digital data signal for controlling display; and a displaycontrol section for performing display control on the basis of thedigital data signal stored by said storing section; provided in each dotas a minimum unit of display and arranged on a semiconductor orinsulating substrate.
 2. A display device, characterized by comprising:a storing section configured by one or a plurality of storing circuitsprovided at each of interconnections of a plurality of write lines and aplurality of data lines correspondingly to an array pattern of a dot asa minimum unit of display so that, when a write signal is transmittedthrough said write line and an image signal as a digital data signal forcontrolling display is transmitted through said data line, the imagesignal is stored; a converting section for converting a value based on avalue of the image signal stored by said storing section into an analogsignal; and a display control section for performing tonal control usinga liquid crystal on the basis of an analog signal converted by saidconverting section; provided in each dot as a minimum unit of displayand arranged on a semiconductor or insulating substrate.
 3. A displaydevice as claimed in claim 2, characterized in that said storing circuitof said storing section is configured by a static circuit.
 4. A displaydevice as claimed in claim 2 or 3, characterized in that said convertingsection pulse-width-modulates the value based on the image signal toconvert the value into the analog signal.
 5. A display device as claimedin claim 2 or 3, characterized in that said converting section convertsthe value based on the image signal into the analog signal modulated toa pulse width based on a γ-characteristic.
 6. A display device asclaimed in claim 2 or 3, characterized in that said converting sectionperforms conversion into the analog signal at a constant periodinterval.
 7. A display device as claimed in claim 6, characterized inthat a duration that no conversion into the analog signal is made isprovided in the constant period.
 8. A display device as claimed in claim7, characterized in that each converting section is different in a starttime of the constant period, and the period and the duration noconversion into the analog signal is made is different.
 9. A displaydevice as claimed in claim 6, characterized in that an alternatingcurrent drive voltage corresponding to the constant period is applied tosaid display control section.
 10. A display device as claimed in claim9, characterized in that the alternating current drive voltage is avoltage driven at VCOM±Va with respect to a reference voltage VCOM. 11.A display device as claimed in claim 9, characterized in that thealternating current drive voltage is a voltagealternating-current-inversion-driven by two voltage-applying lines laidcorrespondingly to said dot array pattern.
 12. A display device asclaimed in claim 9, characterized in that a plurality of rows of saiddot array are provided by groups, and rows in pair are set in each ofthe groups to invert a phase of the alternating current drive voltageapplied.
 13. A display device as claimed in claim 2 or 3, characterizedin that said display control section controls light emission ofcurrent-driven luminescent devices in connection on the basis of theanalog signal in place of performing tonal control using a liquidcrystal, thereby effecting tonal control.
 14. A display device,characterized by comprising: storing section configured by one or aplurality of storing circuits provided at each of interconnections of aplurality of write lines and a plurality of data lines correspondinglyto an array pattern of a dot as a minimum unit of display so that, whena write signal is transmitted through said write line and an imagesignal as a digital data signal for controlling display is transmittedthrough said data line, the image signal is stored; one or a pluralityof active devices provided respectively connected to said storingcircuits of said storing section and current-driven luminescent deviceshaving areas corresponding to place values represented by image signalsstored in said storing circuits, a display control section provided ineach dot to control emission of light of said current-driven luminescentdevices on the basis of the values of the image signals stored in saidstoring circuits, and those are arranged on a semiconductor orinsulating substrate.
 15. A display device as claimed in claim 13 or 14,characterized in that said current-driven luminescent devices arestructured by EL devices.
 16. A display device as claimed in claim 13 or14, characterized in that said current-driven luminescent devices arestructured by organic EL devices.
 17. A display device, characterized bycomprising: a storing section configured by one or a plurality ofstoring circuits provided at each of interconnections of a plurality ofwrite lines and a plurality of data lines correspondingly to an arraypattern of a dot as a minimum unit of display so that, when a writesignal is transmitted through said write line and an image signal as adigital data signal for controlling display is transmitted through saiddata line, the image signal is stored; one or a plurality of activedevices provided respectively connected to said storing circuits of saidstoring section and liquid crystal driving sections having areascorresponding to place values represented by image signals stored insaid storing circuits, a display control section provided in each dot toperform tonal control using a liquid crystal on the basis of the valuesof the image signals stored in said storing circuits, and these arearranged on a semiconductor or insulating substrate.
 18. A displaydevice as claimed in any of claims 2, 3, 14 and 17, characterized byfurther laying a plurality of read lines correspondingly to said dotarray pattern so that, if a read signal is transmitted, the imagesignals stored in said storing circuits are read out of said storingsection.
 19. A display device, characterized by comprising: a displaydrive section having a plurality of word lines, a plurality of writelines and a plurality of data lines laid correspondingly to an arraypattern of a dot as a minimum unit of display, and a display controlsection operating, when at least a write signal is transmitted throughsaid write lines and the image signals are transmitted through said datalines, on the basis of said storing section for storing the imagesignals, the image signals and a word signal transmitted through saidword lines, provided in each of the dot array patterns; a word linedriver section for controlling transmission of a word signal to saidword lines; a row decoder section for selecting a row for transmitting awrite signal to said write lines, to transmit the write signal to aselected row; a column decoder section for selecting said data line; acolumn selection switch section for transmitting the image signals asdata signals for controlling display to said data line selected by saidcolumn decoder section; integrated and integrally formed on asemiconductor or insulating substrate.
 20. A display device as claimedin claim 19, characterized in that a converting section for converting avalue based on the image signals stored in said storing section into ananalog signal is provided in each dot array pattern in said displaydrive section, and said display control section operates on the basis ofthe analog signal and the word signal.
 21. A display device as claimedin claim 19, characterized in that said word lines are laid to transmitthe word signal to said display control section on two rows.
 22. Adisplay device as claimed in claim 19 or 20, characterized in that saidword line driver section and said row decoder section are allocatedcorrespondingly to a length of said display drive section in a columndirection, and said column decoder section and said column selectionswitch section are allocated correspondingly to a length of said displaydrive section in a row direction.
 23. A display device as claimed inclaim 19, characterized in that each column selection switch structuringsaid column selection switch section is allocated correspondingly to awidth of said dot array pattern.
 24. A display device as claimed inclaim 19 or 20, characterized in that said row decoder section selects arow for transmitting the write signal on the basis of an address signalrepresenting a storage position.
 25. A display device an claimed inclaim 23 characterized in that said column decoder section selects saiddata lines on the basis of the address signal.
 26. A display device asclaimed in claim 25, characterized in that three dots for developing anddisplaying in red, blue and green as light source colors are provided asone pixel, the image signals are inputted on a one-pixel-unit basis, andsaid column decoder section selects data lines for storing the imagesignals in an amount of one pixel.
 27. A display device as claimed inclaim 25, characterized in that three dots for developing and displayingin red, blue and green as light source colors are provided as one pixel,the image signals are inputted on a plural-pixel-unit basis, and saidcolumn decoder section selects data lines for storing the image signalsin an amount of a plurality of pixels.
 28. A display device as claimedin claim 19, characterized by further comprising: a timing controllersection for controlling at least timing of transmitting the addresssignal; a memory controller section for controlling transmission of theimage signals; further integrated and integrally formed on saidsubstrate.